Greetings all. I had a comparatively easy gird fill but then ground to a halt. Have now looked again at the thread and see the theme and what needs to be done. Could I ask for three (they may only be two) bits of help to put my mind at rest.
How is 12 across parsed?
In which clue does the first letter of the 8 letter word appear?
In which clue are the penultimate two adjacent letters of the second word of the context?
I'll then have a bash at the substitutions. It has been a most enjoyable stretch in a busy week and I can live without final completion - the workout has been good. So thank you, Hedge-Sparrow